Dogfish Embryo

Description

"Embryo dogfish in egg-case ("mermaid's purse") which has been cut open to show contents. e.g., "External" gills; d.f., dorsal fin fold; y.s., yolk-sac; st., stalk of yolk-sac; T., tendrils, prolongations of egg-case by means of which it is moored to seaweed, and "adaptation" in a dead substance." -Thomson, 1916